Methods of identifying and quantifying products of co-expression of heavy chains and light chains have been previously described. For instance, liquid chromatography-mass spectrometry (LC-MS) and ion exchange chromatography (IEX) have been used to characterize the purity of bi-specific antibody constructs (see, for example, Strop et al. (2012) J. Mol. Biol. 420: 204-219). An activity-based sandwich ELISA has also been used as a high-throughput screen to select stable cell-lines secreting high yields of bi-specific antibodies with good purity. (see for example, van der Neut Kolfschonten et al. (2007), Science 317: 1554-1557). Methods of displaying antibodies using yeast have also been described (see, e.g., Chao et al., Nat Protoc. 2006; 1(2):755-68). Methods of isolating or purifying antibodies using, for example, affinity chromatography are well known in the art and affinity purification columns are commercially available.
A quantitative immunoglobulin heavy chain/light chain immunoassay, Hevylite® (HLC, The Binding Site Group, Birmingham, UK), is commercially available, and includes a step of measuring IgGκ/IgGλ pairs. This assay is used to quantify monclonal immunoglobulins in patients with diseases such as, for example, multiple myeloma.